In a decayed tooth treating method, which is generally used in a dental clinic, a decayed portion of a tooth is first removed using an endodontic file. When the pulp of the tooth is injured, the injured or afected pulp is also removed. Thereafter, a filler, e.g., endodontic cement or sealer, is filled in the portion of the tooth to be treated, namely, the root canal of the tooth, to seal the root canal. Finally, a prosthetic treatment is carried out for the tooth. In the root canal filling procedure, gutta-percha cones are used as a temporary filling material having an auxiliary function for enabling the filler to penetrate into the root canal and thus to seal up the root canal. Gutta-percha, which is a natural vegetable extract, has a semisolid phase at room temperature, but has the form of a solid gum when it is compressed or heated. The gutta-percha having the form of such a solid gum is called “white gutta-percha”.
Generally, gutta-percha cones are prepared by adding zinc oxide, barium sulfate, wax, and pigment to gutta-percha, kneading them into a paste in a mixer, extruding the paste in the form of a sheet using rolls, cutting the sheet into pieces, and shaping the pieces into a conical structure. Thus, gutta-percha cones having various sizes can be formed. Such a gutta-percha cone is most widely used as a material for endodontic treatment that it is known as being most biologically compatible with living bodies because it is harmless to the root apexes of teeth. Gutta-percha cones, which are currently commercially available, are classified into a standardized cone and an accessory cone. The standardized cone has a shape identical to that of a dental file.
In endodontic treatment for a decayed tooth, the affected pulp of the tooth is first drilled to remove affected nerve tissues. Thereafter, a filler coats the root canal wall, in order to prevent the root canal from being further affected by a source of decay. A gutta-percha cone having a suitable size is then inserted into the root canal to fix the filler to the main and accessory portions of the root canal. In this case, it is important to bring the gutta-percha cone into complete contact with the root canal wall and apical area of the tooth.
After completion of the root canal filling procedure, the filling state in the root canal is confirmed using X-ray photography. The gutta-percha cone is then removed. For the removal of the gutta-percha cone, an excavator, an endodontic plugger, or a spreader is used in a state of being heated in flame.
The present invention relates to a gutta-percha filling instrument which applies a gutta-percha cone to a root canal wall in a dental clinic procedure, as mentioned above, such that the gutta-percha cone comes into complete contact with the root canal wall. In particular, the present invention relates to a complete heating type filling instrument for endodontic treatment which fills a root canal with a gutta-percha cone after completing melting the gutta-percha cone, thereby achieving complete filling of the root canal without waste of the gutta-percha cone. This may be explained in conjunction with Obtura II manufactured by Obtura Spartan Company. For endodontic treatment, a method for filling a root canal with gutta-percha is generally used which is carried out by filling about a ⅓ part of the root canal using a filling instrument for back-filling such as System B manufactured by Analytic Company, and then filling the remaining part of the root canal using a complete melting type filling instrument such as Obtura II manufactured by Obtura Spartan Company.
Generally, the complete melting type filling instrument, which is adapted to fill a root canal with gutta-percha, includes a handpiece, and a control box which includes a power source for supplying electric power to the handpiece, and a controller for controlling the handpiece. The handpiece, which is grasped by a doctor for endodontic treatment, is separate from the control box, and is electrically connected with the control box by a cable.
Hereinafter, a conventional complete melting type filling instrument for endodontic treatment will be described with reference to FIGS. 1 to 5. FIG. 1 is a view illustrating an example of a configuration of a conventional complete melting type filling instrument for endodontic treatment. FIG. 2 is a perspective view illustrating a handpiece shown in FIG. 1. FIG. 3 is a plan view illustrating a piston which pushes gutta-percha melted in the handpiece of FIG. 2, to fill a root canal with the gutta-percha.
As shown in the drawings, the conventional gutta-percha filling instrument includes a control box 10 which includes a power switch 11, a control panel 12, and a display 13 for displaying an operation state of the filling instrument. The conventional gutta-percha filling instrument also includes a handpiece 20 which includes a grip 21, a heating coil 25 for supplying heat to gutta-percha, to melt the gutta-percha, a needle-shaped injector 24 for injecting the melted gutta-percha into a root canal, a piston 30 for supplying the melted gutta-percha to the injector 24, and a filling switch 22 for driving the piston 30.
The control box 10 and handpiece 20 are connected to each other by a cable 40. Electric power required by the handpiece 20 is supplied via the cable 40.
A temperature sensor 26 is arranged at the injector 24, to sense the temperature of the injector 24. For the temperature sensor, a platinum sensor may be used which uses platinum exhibiting a variation in resistance depending on a variation in temperature, to measure a temperature based on a measured resistance of the platinum.
As shown in FIG. 2, a charging hole 27 is provided at an upper portion of the handpiece 20 of the filling instrument, to charge an upstream portion of the injector with an endodontic gutta-percha piece which has a certain standardized size. The piston 30, which is shown in FIG. 3, is arranged at the rear of the charging hole 27. Accordingly, when the operator pushes the filling switch 22, a front end 33 of the piston 30 is forwardly moved to push the charged gutta-percha. As a result, the gutta-percha is melted while passing the heating coil 25, and then, is injected into a root canal through the injector 24.
FIG. 4 is a schematic exploded view illustrating an example of the injector included in the conventional complete melting type filling instrument for endodontic treatment. FIG. 5 is a schematic exploded view illustrating another example of the injector included in the conventional complete melting type filling instrument for endodontic treatment. In the case of FIG. 4, the injector 24 includes a needle 24a and a cap 24b. The needle 24a is mounted to a body of the injector 24 by the cap 24b. 
Generally, operators use a needle after bending the needle. When it is desired to perform a task in a direction opposite to the bending direction of the bent needle, the operator must re-bend the needle in the opposite direction. Otherwise, the operator must perform operations of unfastening the cap, turning the needle such that the bending direction of the needle is reversed, and re-fastening the cap to fix the needle. However, it is difficult to easily perform the task because the body and needle of the injector have a temperature of about 200° C. In addition, there is a possibility that the needle 24a may be easily broken after being bent several times in opposite directions because the material thickness of the needle 24a is small. Furthermore, the filler may be leaked because there is no seal member provided at the injector.
In the case of the other conventional injector, as shown in FIG. 5, a needle 24a of the injector 24 is welded to one end of a cap 24b. In this case, when it is necessary to reversely change the bending direction of the needle 24a, the needle 24a must be re-bent in the reverse direction because the needle 24a is in a state of being fixed to the cap 24b. For this reason, the needle 24a may be easily broken.
The above-mentioned conventional gutta-percha filling instrument for endodontic treatment has a problem that there is inconvenience in carrying the filling instrument because the control box 10 and handpiece 20 are separate from each other. Also, there are problems of high manufacturing costs and a complex manufacturing procedure because it is necessary to additionally provide the temperature sensor for sensing the temperature of the heating coil.
Moreover, there is a problem that malfunction or failure occurs due to twisting, bending, or breaking of the cable connecting the control box and handpiece. Also, there is a problem that the operation range is limited because the movement range of the handpiece is limited by the cable. The view of the operator is also limited by the cable.
In addition, there is a problem that the concentration of the operator upon the operation may be degraded because the operator should additionally control the control box which is separate from the handpiece.